Gaze tracking variations using dynamic lighting position

ABSTRACT

Aspects of the present disclosure relate to eye tracking systems and methods which track eyes by illuminating the eyes using a light source and detecting the eye illuminations using a sensor. Implementations of the present disclosure may utilize a light source with a dynamic lighting position to account for changes in lighting conditions during the tracking which interfere with detection of the eye illuminations, such as reflections in glasses which may obscure a user&#39;s eyes.

CLAIM OF PRIORITY

This application claims the priority benefit of commonly-assigned U.S.provisional patent application No. 61/881,656 filed Sep. 24, 2013, theentire disclosures of which are incorporated herein by reference.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to commonly-assigned, co-pending U.S.application Ser. No. 14/493,738, to Eric Larsen, entitled “GAZE TRACKINGVARIATIONS USING LEDs”, filed the same day as the present application,the entire contents of which are herein incorporated by reference.

This application is related to commonly-assigned, co-pending U.S.application Ser. No. 14/493,766, to Eric Larsen, entitled “GAZE TRACKINGVARIATIONS USING VISIBLE LIGHTS OR DOTS”, filed the same day as thepresent application, the entire contents of which are hereinincorporated by reference.

FIELD

The present disclosure relates to eye gaze tracking. In particular,aspects of the present disclosure relate to light sources for opticaleye gaze tracking systems.

BACKGROUND

Eye gaze tracking has use in a wide range of applications, includingmedical research, automobile technology, computer entertainment andvideo game programs, control input devices, augmented reality glasses,and more.

Some known eye gaze tracking techniques involve illuminating the eyes byemitting light from one or more light sources and detecting reflectionsof the emitted light off of the eyes with a sensor. Typically, this isaccomplished using invisible light sources in the infrared range andcapturing image data (e.g., images or video) of the illuminated eyeswith an infrared sensitive camera. Image processing algorithms are thenused to analyze the image data to determine eye gaze direction.

Generally, eye tracking image analysis takes advantage ofcharacteristics distinctive to how light is reflected off of the eyes todetermine eye gaze direction from the image. For example, the image maybe analyzed to identify eye location based on corneal reflections in theimage data, and the image may be further analyzed to determine gazedirection based on a relative location of the pupils in the image.

Two common gaze tracking techniques for determining eye gaze directionbased on pupil location are known as Bright Pupil tracking and DarkPupil tracking. Bright Pupil tracking involves illumination of the eyeswith a light source that is substantially in line with the optical axisof the camera, causing the emitted light to be reflected off of theretina and back to the camera through the pupil. The pupil presents inthe image as an identifiable bright spot at the location of the pupil,similar to the red eye effect which occurs in images during conventionalflash photography. Dark Pupil tracking involves illumination with alight source that is substantially off line from the optical axis of thecamera, causing light directed through the pupil to be reflected awayfrom the optical axis of the camera, resulting in an identifiable darkspot in the image at the location of the pupil.

In order to effectively determine the desired eye gaze characteristics(e.g., eye position, gaze direction, and the like), these trackingtechniques generally rely on the tracking system's ability toeffectively illuminate the user's eyes with the light source andeffectively detect the corresponding reflections of the emitted lightoff of these eyes. Unfortunately, in many traditional systems,environmental factors and other factors such as variable lightingconditions can interfere with the tracking system's ability to performthese functions, causing poor tracking performance and intermittentoperation.

It is within this context that aspects of the present disclosure arise.

SUMMARY

An implementation of the present disclosure may include a methodcomprising: emitting light from an eye tracking device; capturing one ormore images with the eye tracking device of an area illuminated by saidemitting the light; determining one or more gaze characteristics fromanalysis of the images based on eye illuminations within the images fromsaid emitting the light; analyzing the images to detect a pre-definedchange in lighting conditions in the images; and triggering a change ofa position of a source of the light upon detection of the pre-definedchange in the light conditions. The pre-defined change may be anoccurrence of glare which interferes with the eye illuminations in theimages. The eye tracking device may have a plurality of light sources,wherein said emitting the light includes initially emitting the lightfrom one or more first light sources selected from the plurality oflight sources and, after said change in the position, emitting lightfrom one or more second light sources selected from the plurality oflight sources which are different from the first light sources, andwherein said triggering the change includes triggering a change fromemitting the light from the first light sources to emitting light fromthe second light sources.

Another implementation may include a system comprising: an eye trackingdevice; and a computing device, wherein the system is configured toperform a method, the method comprising: emitting light from the eyetracking device; capturing one or more images with the eye trackingdevice of an area illuminated by said emitting the light; determiningone or more gaze characteristics from analysis of the images with thecomputing device based on eye illuminations within the images from saidemitting the light; analyzing the images with the computing device todetect a pre-defined change in lighting conditions in the images; andtriggering a change with the computing device of a position of a sourceof the light upon detection of the pre-defined change in the lightconditions.

Another implementation of the present disclosure may include anon-transitory computer readable medium having processor-executableinstructions embodied therein, wherein execution of the instructions bya processor causes a processor to perform a method, the methodcomprising: emitting light from an eye tracking device; capturing one ormore images with the eye tracking device of an area illuminated by saidemitting the light; determining one or more gaze characteristics fromanalysis of the images based on eye illuminations within the images fromsaid emitting the light; analyzing the images to detect a pre-definedchange in lighting conditions in the images; and triggering a change ofa position of a source of the light upon detection of the pre-definedchange in the light conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present disclosure can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIGS. 1A-1D is a process flow diagram depicting an eye tracking deviceand a method of tracking eyes with the eye tracking device to illustratevarious aspects of the present disclosure

FIG. 2 is a flow diagram depicting an example method of eye tracking toillustrate various aspects of the present disclosure.

FIG. 3 is a block diagram depicting an example of a system for eyetracking to illustrate various aspects of the present disclosure.

DETAILED DESCRIPTION

Although the following detailed description contains many specificdetails for the purposes of illustration, anyone of ordinary skill inthe art will appreciate that many variations and alterations to thefollowing details are within the scope of the invention. Accordingly,the exemplary embodiments of the invention described below are set forthwithout any loss of generality to, and without imposing limitationsupon, the claimed invention.

Introduction

Eye tracking devices may utilize a lighting source to illuminate eyes,and a camera to capture images of the illuminated eyes. The eyeilluminations contained in the images may then be analyzed to determinethe desired eye gaze characteristics, such as eye position, eyemovements, gaze direction, gaze point, and the like. However, onechallenge with such systems is that variations in lighting conditionsmay cause interference with the ability of the tracking system tocapture images of the eye illuminations used to determine the desiredgaze characteristics. For example, many people wear eyeglasses, whichsometimes cause reflections that obscure the eyeglass wearer's eyes inimages captured with the eye tracking device. As a user moves around orchanges head position, changes in head orientation with respect to theeye tracking device may cause reflections off of the glasses whichobscure the user's eyes in the images, and the eye gaze tracking maybecome intermittent as a result.

According to aspects of the present disclosure, variations in lightingconditions which interfere with eye tracking may be accounted for usingan eye tracking device having a dynamic lighting position. As sources ofinterference due to lighting conditions are detected in the images, alighting position of the eye tracking device may be changed, alteringthe lighting conditions for the images captured with the eye trackingdevice and providing clearer images of the eye illuminations that mayanalyzed to determine gaze characteristics.

Implementation Details

An illustrative process flow of an example system 100 and method of eyetracking is depicted in FIGS. 1A-1D. In the implementation depicted inFIGS. 1A-1D, an eye tracking device having a dynamic lighting positionis used to illuminate eyes and capture images of the illuminated eyes.

The images may be analyzed to determine one or more gaze characteristicsof the eyes, and the position of the lighting may change during theillumination based upon analysis of the images.

As shown in FIG. 1A-1D, the example system 100 may include an eyetracking device having a dynamic lighting source 110 and a camera 112which is sensitive to light emitted from the lighting source 110. By wayof example, and not by way of limitation, the light emitted from thedynamic lighting source 110 may be invisible light such as infraredlight, and the camera 112 may be an infrared sensitive camera. Thesystem 100 may also include a display device 104 which may operate incoordination with the eye tracking device for various eye trackingapplications, e.g., to determine a user's gaze point on the screen. Thecamera 112 may be located above the display device 104 or below thedisplay device. It may be advantageous to locate the camera 112 abovethe display device, since eyes tend to be less obscured when viewed frombelow eye level.

In order to perform eye tracking, the system 100 may emit light from thedynamic lighting source 110 and capture images 111 a-d of an areailluminated by light with the camera 112 of the eye tracking device. Theimages 111 a-d may contain images of a user 106, whose face and eyes areilluminated by the emitted light, and the images may 111 a-d may beanalyzed by a computing device (not separately pictured) which mayprocess the images to determine one or more characteristics of the eyegaze of the user 106 based on analysis of the illuminations of theuser's eyes. In one implementation, this may involve analyzing theimages 111 a-d to identify eye illuminations, including cornealreflections caused by the emitted light and/or one or more Dark Pupils(i.e. a dark spot at a pupil location of an eye illuminated by lightthat is off-axis from the camera 112). These characteristic eyeilluminations in the images 111 a-d may be analyzed to determine thedesired gaze characteristics, such as eye position, eye movements, gazedirection, gaze point, and the like, using suitable image processingalgorithms processed with the computing device.

As shown in FIG. 1A, the light from the dynamic lighting source 110 maybe initially emitted from one or more initial positions 105 a. In theexample illustrated in FIG. 1A, the initial light source position 105 aincludes a plurality of light sources horizontally offset from oneanother at an initial vertical position, and the dynamic lighting source110 includes a plurality of discrete light sources disposed at differentlocations. The eye tracking device may capture images 111 a of theilluminated user 106 with the camera 112 of the eye tracking device, andthe user may have an initial head orientation and eye gaze direction asshown in FIG. 1A.

As shown in FIG. 1B, the system 100 may continue to track the eyes ofthe user 106, and the images 111 b of the user 106 depict a user havinga changed eye gaze direction. By way of example, the image 111 bdepicted in FIG. 1B may include a Dark Pupil at a different locationfrom a Dark Pupil in the image 111 a in FIG. 1A, and this Dark Pupil maybe analyzed to determine a gaze direction of the user 106 based on thelocation of this Dark Pupil. Moreover, as illustrated in FIG. 1B, theimages 111 b of the user 106 are clear and generally free frominterfering lighting conditions which interfere with the capture of theeye illuminations. For example, while the user 106 is wearing eyeglasses107, a clear image of the user's illuminated eyes is still captured bythe camera 112 through the glasses 107. Accordingly, the initial sourceposition 105 a of the emitted light may be maintained.

Turning to FIG. 1C, the head orientation of the user 106 has changedrelative to the system 100. In particular, the user's head orientationrelative to the lighting source 110 and the camera 112 has changed. As aresult of the orientation of the user's eyeglasses 107 relative to thecomponents 110, 112 of the eye tracking device, light emitted from theinitial lighting position 105 a causes glare 109 from the user'seyeglasses due to reflections of the emitted light off of the glasses.As a result, in the image 111 c of the user, the user's eyes areobscured by the glare 109, and the system 100 may be unable to determinethe desired gaze characteristics from analysis the eye illuminations.For example, this glare may obscure a dark spot (i.e. Dark Pupil) in theimages at a location of the eyes that is used to determine gazedirection. The changed lighting conditions present in FIG. 1C mayinterfere with tracking data gathered by the system 100, causing thetracking to become intermittent.

As shown in FIG. 1D, upon occurrence of these changed lightingconditions, the source position of the lighting may change to a newposition 105 b in order to account for the changed lighting conditions.As a result, as shown in the image 111 d in FIG. 1D, the glare from theuser's glasses 107 is removed due to the change in position of thelighting source 110, and a clearer image of the user's eyes is obtained.By way of example, a Dark Pupil in the image 111 c may be identifiableby the system 100 and not obscured by glare, even though the user's headorientation with respect to the remaining components of the system 100is unchanged.

In one implementation of the present disclosure, the change in lightingposition depicted in FIG. 1D may be triggered automatically by thesystem 100 and may occur virtually instantaneously, e.g. by usingprogramming or a suitable configuration of a computing device coupled tothe dynamic lighting source 110. By way of example, the computing devicemay continuously analyze the one or more images captured by the camera112, which may be a plurality of still images or a video in the form ofa “moving image”, in order to detect a pre-defined change in the lightconditions of the tracking environment. For example, the system maydetect that glare is present in the images in a location that interfereswith image capture of the eye illuminations, or the analysis may be usedto detect some other change which caused the tracking performance todegrade or become intermittent. Upon detecting these conditions thesystem may automatically send a control signal to the dynamic lightingsource 110, which causes the position to change to new position 105 b.The net affect may be a system which dynamically adjusts the lightingposition in real-time as lighting conditions change in the capturedimages, minimizing or preventing any intermittence in the eye gazetracking and/or otherwise improving tracking performance.

In the example depicted in FIGS. 1A-1D, the dynamic lighting source 110is depicted as a plurality of discrete light sources, such as infraredLEDs which each emit invisible light, and the different light sourcesare each fixed in a different location in the illustratedimplementation. More specifically, the dynamic light source 110 in theillustration of FIG. 1D is depicted as a plurality of sets of lightsources, with each of the sets having a plurality of light sourcesoffset from each other in a vertical direction. In FIGS. 1A-1D, theplurality of sets is arranged as two vertical bars disposed on opposingsides of a display device 104, and each of the vertical bars has aplurality of light sources arranged in a line, and, as shown in FIG. 1D,the lighting position may be moved in a vertical direction up and down,e.g., by selectively turning off and on various ones of the lightsources based on present lighting conditions detecting from analysis ofthe images 111 a-d.

It will be readily understood that a dynamic lighting source inaccordance with aspects of the present disclosure may be arranged in avariety of different implementations having a variety of differentconfigurations. For example, the plurality of light sources depicted inFIGS. 1A-1D may be configured in any of a variety of geometricorientations, and any arbitrary number of discrete light sources ordifferent light sources positions may be used. In one implementation,different light sources within a set may be offset from each other in avertical direction, offset in a horizontal direction, or offset in bothhorizontal and vertical directions, such as by having a diagonal layoutor curved configuration. For example, they may be arranged in a fully orpartially circular or elliptical configuration around the displaydevice, or around the camera, or in some other location, in which casethey would be offset from each other in both a horizontal and verticaldirections due to the curvature. In another example, some or all of thelight sources may be arranged behind the display device 104, in whichcase the display device may be configured to transmit whateverwavelength of light is emitted by the light sources.

By way of further example, it may be possible to use some motorized orother electronically movable lighting source in order to change theposition of the light source used to illuminate the user's eyes. In yetanother example, an optical system involving steerable mirrors or sometype of optical switching system may change the light source position inaccordance with various aspect described herein.

Likewise, the system may be configured to change lighting positionsmultiple times before settling on a current position in order todetermine an optimal light source position that accounts for the presentlight conditions. Furthermore, whatever configuration is used, thesystem may be calibrated to account for the changes in light position byprocessing the images based on the present light source location. Anexample of a calibration method which may be used in implementations ofthe present disclosure is describe in U.S. application Ser. No.14/493,766, to Eric Larsen, entitled “GAZE TRACKING VARIATIONS USINGVISIBLE LIGHTS OR DOTS”, filed the same day as the present application,the entire contents of which are herein incorporated by reference. Inanother example, some or all of the components may be built into acommon device, such a display device including the plurality of lightsources or other variable lighting fixed in its casing.

It is further noted that in the example depicted in FIGS. 1A-1D, thecamera 112 is stationary during the eye tracking while the light sourceposition is dynamic. As a result, the light source position relative tothe camera may changes as the position is adjusted in real-time toaccount for the changes lighting conditions. Therefore, it may bepreferred to utilize Dark Pupil tracking so that a plurality ofdifferent light source positions which are off-set from the optical axisof the camera 112 may be used in order to affect the direction fromwhich the illumination originates to a significant enough degree,without having to keep the camera in-line with the optical axis for aBright Pupil tracking system. However, it is noted that it may bepossible to use a Bright Pupil tracking system with a dynamic lightingposition in accordance with aspects of the present disclosure. Forexample, a system having a dynamic camera position coordinated with thedynamic lighting position may be used in an alternative implementationof the present disclosure, such as a system with multiple cameras.

It is further noted that other features may be included in the examplesystem 100. By way of example, the lighting source 110 may includepulsed lighting in the form of pulsed LEDs in order to filter outenvironmental lighting (e.g., due to environmental infrared radiationsources such as the sun). The system 100 may be configured to processonly the eye illuminations that are in pulsed in coordination with theemitted signal in order to filter out the environmental lighting, e.g.,as a way of pulse coding the light signal emitted from the lightingsource 110 of the tracking device. By way of further example, the camera112 may use a global shutter that is timed in sync with the LEDs of thelighting source 110. The LEDs may be controlled to illuminate only whenthe shutter is open, allowing for a brighter LED signal that would bebrighter than environmental light during the time that the shutter isopen.

An example of an eye tracking method 200 using dynamic lighting isdepicted in FIG. 2 to illustrate various aspects of the presentdisclosure. In implementations of the present disclosure, some or all ofthe example method 200 may be performed by a computing device coupled toan eye tracking device which is configured to illuminate eyes usingvariable lighting, such as the example system 100 depicted in FIGS.1A-1D.

The example method 200 includes gathering eye tracking data 230 with aneye tracking device, which may include emitting light from a lightsource 250 (e.g. infrared light) of the eye tracking device anddetecting an area illuminated by the emitted light 252 (e.g. bycapturing one or more infrared images of the illuminated area). Theimages may be processed to identify eye illuminations in the images 254of one or more eyes illuminated by the emitted light, e.g., byidentifying a face and/or by identifying corneal reflections of theemitted light in the images. Processing of the images may be performed,e.g., by a computing device coupled to a camera of the eye trackingdevice and which is configured to process the eye tracking data.

The eye illuminations identified in the images may be analyzed by thecomputing device to determine one or more gaze characteristics 256, suchas eye position, eye movements, gaze direction, gaze point, etc., orsome combination thereof. By way of example, this may be performed usinga Dark Pupil image processing technique in which a dark spot at thelocation of the eye illuminations that is indicative of a pupil locationis analyzed to determine a relative direction of the gaze of a user. Byway of further example, this may involve determining a gaze point or apoint of regard on a display device from analysis of the eyeilluminations, such as the display device 104 of FIGS. 1A-1D.

The images captured by the eye tracking device may also be analyzed,e.g. periodically or continuously while the eyes are being tracked 256,to detect a change in lighting conditions 251 which interferes withimage capture of the eye illuminations. In one implementation, this mayinvolve analyzing the images to detect a presence of a glare whichinterferes with the eye illuminations based upon pre-defined parametersthat indicate a presence of the glare. By way of example, this mayinvolve analyzing an area of the images which corresponds with a DarkPupil to detect a presence of a bright spot. When the analysis detectsthat this bright spot is present, or when a size and/or intensity ofsuch a bright spot exceeds some pre-defined threshold, this may indicatethat the pre-defined change in lighting conditions 251 has been met. Forexample, such a bright spot may indicate that glare from a user'seyeglasses is obscuring the eye illuminations being used to determinethe gaze characteristics 256.

Upon determining that the pre-defined change in light conditions hasbeen met, the computing device may trigger a change in a source location253 of the emission of light 250 from the eye tracking device, e.g., asshown and described in FIGS. 1C-1D above. By way of example, thecomputing device may be in communication with a dynamic light source ofthe eye tracking device, and the computing device may send a controlsignal that changes a position of the light. In one example, this mayinvolve turning off one or more LEDs and turning on one or moredifferently located LEDs, thereby causing the light to illuminate theeye from a different location and potentially improving the lightingconditions contained in the images for eye gaze tracking. If the changein light conditions has not occurred, as determined at 251, the methodmay continue to analyze the images as normal, with no change in thelight source location. By way of example, this operation depicted in theexample method 200 may be performed continuously during the eye trackingin real-time in order to dynamically adjust the lighting position on thefly.

FIG. 3 depicts an example system for eye tracking 300 to furtherillustrate various aspects of the present disclosure. The example system300 may include a computing device 360 which is coupled to an eyetracking device 302 and a display device 304 in order to perform eyegaze tracking and/or calibration for eye tracking in accordance withaspects of the present disclosure. The display device 386 may be in theform of a cathode ray tube (CRT), flat panel screen, touch screen, orother device that displays text, numerals, graphical symbols, or othervisual objects. According to aspects of the present disclosure, thecomputing device 360 may be an embedded system, mobile phone, personalcomputer, tablet computer, portable game device, workstation, gameconsole, and the like. Moreover, the computing device 360, the eyetracking device 302, the display device 304, or any combination thereofmay form an integral unit or be implemented as separate components whichmay be in communication with each other.

The eye tracking device 302 may be coupled to the computing device 360,and may include a dynamic lighting source 310 similar to light sources110 of FIGS. 1A-1D. By way of example, and not by way of limitation, thelighting source 310 may be an invisible lighting source in the form ofone or more infrared LEDs, which may be configured to illuminate auser's eyes in order to gather eye tracking data with the sensor 312,and which may have a position which is electronically controllable todifferent positions, e.g., as shown in FIGS. 1A-1D. The sensor 312 ofthe eye tracking device may be a detector which is sensitive to lightemitted from the light source 310. For example, the sensor 312 may be acamera sensitive to the light source such as an infrared camera, and thecamera 312 may be positioned relative to the eye tracking device and thelighting source so that it may capture images of an area illuminated bythe lighting source 310.

The computing device 360 may be configured to operate in coordinationwith the eye tracking device 302 and the display device 304, in order toperform eye gaze tracking and determine lighting conditions inaccordance with aspects of the present disclosure. The computing device360 may include one or more processor units 370, which may be configuredaccording to well-known architectures, such as, e.g., single-core,dual-core, quad-core, multi-core, processor-coprocessor, cell processor,and the like. The computing device 360 may also include one or morememory units 372 (e.g., random access memory (RAM), dynamic randomaccess memory (DRAM), read-only memory (ROM), and the like).

The processor unit 370 may execute one or more programs, portions ofwhich may be stored in the memory 372, and the processor 370 may beoperatively coupled to the memory 372, e.g., by accessing the memory viaa data bus 376. The programs may be configured to perform eye gazetracking and determine lighting conditions for the system 300. By way ofexample, and not by way of limitation, the programs may include dynamiclighting source gaze tracking programs 374, execution of which may causethe system 300 to perform a method having one or more features in commonwith the method of FIG. 2. By way of example, and not by way oflimitation, the gaze tracking programs 374 may include processorexecutable instructions which cause the system 300 to determine one ormore gaze tracking parameters of the system 300 from eye tracking datagathered with the camera 312 while light is emitted from the dynamiclighting source 310. The gaze tracking programs 374 may also includeinstructions which analyze images gathered with the camera 312 in orderto detect a presence of a change in lighting conditions, e.g., asdescribed above with respect to FIG. 2.

The computing device 360 may also include well-known support circuits378, such as input/output (I/O) circuits 379, power supplies (P/S) 380,a clock (CLK) 381, and cache 382, which may communicate with othercomponents of the system, e.g., via the bus 376. The computing device360 may optionally include a mass storage device 384 such as a diskdrive, CD-ROM drive, tape drive, flash memory, or the like, and the massstorage device 384 may store programs and/or data. The computing device360 may also include a user interface 388 to facilitate interactionbetween the system 300 and a user. The user interface 388 may include akeyboard, mouse, light pen, game control pad, touch interface, or otherdevice.

The system 300 may also include a controller (not pictured) whichinterfaces with the eye tracking device 302 in order to control thesource position of the lighting source 310 based on the image analysisof the gaze tracking programs 374. The system 300 may also execute oneor more general computer applications (not pictured), such as a videogame, which may incorporate aspects of eye gaze tracking as sensed bythe tracking device 302 and processed by the tracking programs 374.

The computing device 360 may include a network interface 390, configuredto enable the use of Wi-Fi, an Ethernet port, or other communicationmethods. The network interface 390 may incorporate suitable hardware,software, firmware or some combination thereof to facilitatecommunication via a telecommunications network. The network interface390 may be configured to implement wired or wireless communication overlocal area networks and wide area networks such as the Internet. Thecomputing device 360 may send and receive data and/or requests for filesvia one or more data packets 399 over a network.

It will readily be appreciated that variations on the componentsdepicted in FIG. 3 are possible, and that various ones of thesecomponents may be implemented in hardware, software, firmware, or somecombination thereof. For example, the some features or all features ofthe calibration programs contained in the memory 372 and executed by theprocessor 370 may instead be implemented via suitably configuredhardware, such as one or more application specific integrated circuits(ASIC).

CONCLUSION

It is noted that aspects of the present disclosure have been describedwith reference to eye tracking devices that use infrared light sources,which has developed as a relatively standard light source for opticaleye tracking techniques. However, it is understood that otherimplementations are possible. For example, in implementations of thepresent disclosure, other invisible light sources are possible, such asultraviolet light. By way of further example, in implementations of thepresent disclosure, visible light sources are possible for eyeillumination, although it may be desirable to use invisible lightsources in order to avoid distracting a user.

While the above is a complete description of the preferred embodiment ofthe present invention, it is possible to use various alternatives,modifications and equivalents. Therefore, the scope of the presentinvention should be determined not with reference to the abovedescription but should, instead, be determined with reference to theappended claims, along with their full scope of equivalents. Any featuredescribed herein, whether preferred or not, may be combined with anyother feature described herein, whether preferred or not. In the claimsthat follow, the indefinite article “a”, or “an” refers to a quantity ofone or more of the item following the article, except where expresslystated otherwise. The appended claims are not to be interpreted asincluding means-plus-function limitations, unless such a limitation isexplicitly recited in a given claim using the phrase “means for.”

What is claimed is:
 1. A method comprising: emitting light from an eyetracking device; capturing one or more images with the eye trackingdevice of an area illuminated by said emitting the light; determiningone or more gaze characteristics from analysis of the images based oneye illuminations within the images from said emitting the light;analyzing the images to detect a pre-defined change in lightingconditions in the images; and triggering a change of a position of asource of the light upon detection of the pre-defined change in thelight conditions.
 2. The method of claim 1, wherein the pre-definedchange is an occurrence of glare which interferes with the eyeilluminations in the images.
 3. The method of claim 1, wherein saiddetermining the gaze characteristics based on the eye illuminationsincludes analyzing a Dark Pupil in the images which is generated by saidemitting the light, wherein said analyzing the images to detect thepre-defined change in lighting conditions includes analyzing a locationof the Dark Pupil for a bright spot at the location which exceeds apre-defined size threshold, a pre-defined intensity threshold, or acombination thereof.
 4. The method of claim 1, wherein the eye trackingdevice has a plurality of light sources, wherein said emitting the lightincludes initially emitting the light from one or more first lightsources selected from the plurality of light sources and, after saidchange in the position, emitting light from one or more second lightsources selected from the plurality of light sources which are differentfrom the first light sources, and wherein said triggering the changeincludes triggering a change from emitting the light from the firstlight sources to emitting light from the second light sources.
 5. Themethod of claim 4, wherein the plurality of light sources are infraredLEDs, wherein the images are infrared images, and wherein triggering thechange includes turning off the first infrared LEDs and turning on thesecond infrared LEDs.
 6. The method of claim 4, wherein the second lightsources are offset from the first light sources in a vertical direction.7. The method of claim 4, wherein the pre-defined change is anoccurrence of glare which interferes with the eye illuminations in theimages.
 8. The method of claim 1, wherein said determining the gazecharacteristics includes determining a gaze direction.
 9. A systemcomprising: an eye tracking device; and a computing device, wherein thesystem is configured to perform a method, the method comprising:emitting light from the eye tracking device; capturing one or moreimages with the eye tracking device of an area illuminated by saidemitting the light; determining one or more gaze characteristics fromanalysis of the images with the computing device based on eyeilluminations within the images from said emitting the light; analyzingthe images with the computing device to detect a pre-defined change inlighting conditions in the images; and triggering a change with thecomputing device of a position of a source of the light upon detectionof the pre-defined change in the light conditions.
 10. The system ofclaim 9, wherein the eye tracking device has a plurality of lightsources, wherein said emitting the light includes initially emitting thelight from one or more first light sources selected from the pluralityof light sources and, after said change in the position, emitting lightfrom one or more second light sources selected from the plurality oflight sources which are different from the first light sources, andwherein said triggering the change includes triggering a change fromemitting the light from the first light sources to emitting light fromthe second light sources.
 11. The system 10, The method of claim 4,wherein the plurality of light sources are infrared LEDs, wherein theimages are infrared images, and wherein triggering the change includesturning off the first infrared LEDs and turning on the second infraredLEDs.
 12. The system of claim 10, wherein the pre-defined change is anoccurrence of glare which interferes with the eye illuminations in theimages.
 13. The system of claim 9, wherein the eye tracking device hasone or more sets of light sources, wherein each said set has a pluralityof light sources offset in a vertical direction with respect to eachother, wherein said emitting the light includes initially emitting thelight from one or more first light sources selected from each of thesets of the light sources and, after said change in the position,emitting light from one or more second light sources selected from eachof the sets of the light sources which are different from the firstlight sources, and wherein said triggering the change includestriggering a change from emitting the light from the first light sourcesto emitting light from the second light sources.
 14. The system of claim13, wherein the one or more sets are a plurality of sets of lightsources, wherein each of the plurality of the sets are horizontallyoffset from each other.
 15. The system of claim 9, wherein thepre-defined change is an occurrence of glare which interferes with theeye illuminations in the images.
 16. The system of claim 9, wherein saiddetermining the gaze characteristics based on the eye illuminationsincludes analyzing a Dark Pupil in the images which is generated by saidemitting the light, wherein said analyzing the images to detect thepre-defined change in lighting conditions includes analyzing a locationof the Dark Pupil for a bright spot at the location which exceeds apre-defined size threshold, a pre-defined intensity threshold, or acombination thereof.
 17. The system of claim 9, wherein said determiningthe gaze characteristics includes determining a gaze direction.
 18. Anon-transitory computer readable medium having processor-executableinstructions embodied therein, wherein execution of the instructions bya processor causes a processor to perform a method, the methodcomprising: emitting light from an eye tracking device; capturing one ormore images with the eye tracking device of an area illuminated by saidemitting the light; determining one or more gaze characteristics fromanalysis of the images based on eye illuminations within the images fromsaid emitting the light; analyzing the images to detect a pre-definedchange in lighting conditions in the images; and triggering a change ofa position of a source of the light upon detection of the pre-definedchange in the light conditions.
 19. The non-transitory computer readablemedium of claim 18, wherein the pre-defined change is an occurrence ofglare which interferes with the eye illuminations in the images.
 20. Thenon-transitory computer readable medium of claim 18, wherein thepre-defined change is an occurrence of glare which interferes with theeye illuminations in the images, wherein the eye tracking device has aplurality of light sources, wherein said emitting the light includesinitially emitting the light from one or more first light sourcesselected from the plurality of light sources and, after said change inthe position, emitting light from one or more second light sourcesselected from the plurality of light sources which are different fromthe first light sources, and wherein said triggering the change includestriggering a change from emitting the light from the first light sourcesto emitting light from the second light sources.